1. Related Field
The present invention relates to milking equipment and, more particularly, to a milking cluster of teat cups and a distributor device for mounting with the cluster and for distributing treatment fluid to the teat cups of the cluster, post milking.
2. Description of Related Art
Conventionally, milking equipment installed in a milking parlour comprises a milking point at each animal stall within the parlour. Each milking point includes a milking cluster of teat cups for connecting the milking equipment to the teats of an animal to be milked. In the case of cows, for example, each milking cluster has four teat cups. The cluster additionally comprises a claw or clawpiece which connects short pulse tubes and short milk tubes leading from the teat cups, respectively, to a long pulse tube coupled to a pulsator and a long milk tube connected to a milk collection system. Each teat cup comprises a rigid hollow shell supporting a resilient or flexible liner which has a barrel portion for engaging about a teat and which has, at its upper end, an head portion with a mouth through which the teat is engaged with the barrel of the liner. At the opposite discharge end of the teat cup, the liner communicates with a short milk tube which delivers milk extracted from an animal's teat to the claw where it is collected and delivered to the long milk tube. A short pulsator tube is connected, at one end, to the annular space or pulse chamber between the shell and the liner and, at its opposite end, is connected, via a device on the claw, to the long pulsation tube and a pulsator.
Upon commencement of milking, vacuum is applied to the teat cups of a milking cluster at each milking point via the long milk tube, the claw and the short milk tubes for the purposes of extracting milk from the teat cups. This vacuum also leaks between the barrel of each liner and the engaged teat and is applied to a void formed about the teat in the head of a liner in order to capture the cup on the teat. Milking is performed by automatically and alternately applying vacuum and atmospheric pressure pulses produced by the pulsator to the pulse chamber of each teat cup in order to flex the liner and stimulate discharge of milk from the engaged teat. It is customary to apply these pneumatic pulses alternately to pairs of teat cups of a cluster.
After completion of the milking cycle, the milking cluster at each milking point is withdrawn from the teats (commonly referred to as “take-off”), such as by an automatic cluster remover and, in a treatment and cleansing cycle, the teats are disinfected and the teat cup liners are flushed internally with disinfectant and water and are dried with compressed air. To this end, teat cups may be fitted with injection nozzles for injecting treatment fluids into the heads of the liners as described in international publication No. WO 2005/043986. The treatment fluid is fed to the injection nozzles via a distributor on the claw. Alternatively, or in addition, treatment fluids may be supplied to each teat cup via a back flush valve disposed at the discharge end of the teat cup. In either event, upon take-off, the milking cluster is designed to enable the short milk tubes to fall away from the centre line of the cluster so that the teat cups are inverted and hang with their heads downwardly from the claw in a rest position. Flushing may be performed with the teat cups in this rest position. Consequently, liquid can escape through the head portions of the teat cups.
Where treatment fluids are injected into the liners of the teat cups, post milking, for example, as described in the aforementioned international publication, the treatment fluid is delivered to the different teat cups of a milking cluster via a distributor on the claw and a safety valve, which is desirably included with the distributor, is provided to prevent treatment fluid entering the liners and contaminating the milk in the event of a control system malfunction. The safety valve provides protection against manifold valve malfunction during the milking cycle and ensures that, in the event of a malfunction which causes treatment fluid under pressure to be fed to the distributor, this is controlled by the safety valve. As described in international application No. WO 2005/102035, during the milking cycle, the safety valve is open to a drain port so that treatment fluid can flow to waste instead of risking the possibility of this treatment fluid contaminating the milk.